csUnit

Inspired by JUnit, csUnit brings the power of unit testing to the .NET framework. csUnit is your key to unit testing and test-driven development using .NET languages such as C#, Visual Basic .NET, Visual J#, or Managed C++. csUnit provides versions for VS2002, VS2003, and VS2005 with add-in support. Of course there is also a stand-alone GUI application and a command line. csUnit is open-source but its license (zlib/libpng) also allows for using csUnit or parts of it in closed-source and commercial projects.